How does keyboard works

As the two plates are brought closer together, it affects the amount of current flowing through the matrix at that point. The processor detects the change and interprets it as a keypress for that location. Capacitive switch keyboards are expensive, but do not suffer from corrosion and have a longer life than any other keyboard. Also, they do not have problems with bounce since the two surfaces never come into actual contact. Metal contact and foam element keyboards are not as common as they used to be.

Metal contact switches simply have a spring-loaded key with a strip of metal on the bottom of the plunger. When the key is pressed, the metal strip connects the two parts of the circuit. The foam element switch is basically the same design but with a small piece of spongy foam between the bottom of the plunger and the metal strip, providing for a better tactile response. Both technologies have good tactile response, make satisfyingly audible "clicks" and are inexpensive to produce.

The problem is that the contacts tend to wear out or corrode faster than on keyboards that use other technologies. Also, there is no barrier that prevents dust or liquids from coming in direct contact with the circuitry of the key matrix.

From the Keyboard to the Computer As you type, the processor in the keyboard is analyzing the key matrix and determining what characters to send to the computer. It maintains these characters in a buffer of memory that is usually about 16 bytes large. It then sends the data in a stream to the computer via some type of connection.

Normal DIN connectors are rarely used anymore. No matter which type of connector is used, two principal elements are sent through the connecting cable. The first is power for the keyboard. Keyboards require a small amount of power, typically about 5 volts, in order to function. The cable also carries the data from the keyboard to the computer. The other end of the cable connects to a port that is monitored by the computer's keyboard controller.

This is an integrated circuit IC whose job is to process all of the data that comes from the keyboard and forward it to the operating system.

When the operating system is notified that there is data from the keyboard, a number of things can happen:. Once the keyboard data is identified as either system-specific or application-specific, it is processed accordingly. The really amazing thing is how quickly all of this happens. As I type this article, there is no perceptible time lapse between my fingers pressing the keys and the characters appearing on my monitor.

When you think about everything the computer is doing to make each single character appear, it is simply incredible! Revised: November 21, About Us. Why US. Virus Alerts. Refer A Friend. Site Map. Privacy Policy. Make Payment. How Keyboards Work by Jeff Tyson. The part of the computer that we come into most contact with is probably the piece that we think about the least. But the keyboard is an amazing piece of technology.

For instance, did you know that the keyboard on a typical computer system is actually a computer itself? First, a switch beneath the key closes, and current flows into a small chip in a keyboard. Each key has a scan code number, which corresponds to its position on the keyboard. The CPU is running the operating system, which constantly checks for key presses. As soon as the OS detects a key press, it immediately reacts and figures out where the data needs to go.

The OS knows what software was active when the key was pressed, and based on this information, creates an event. In computing, an event is an action recognised and handled by software. Your OS knows the layout for your keyboard. It matches the scan code to the key pressed and the associated letter, converting the scan code into a Unicode number. Your text editing software then captures the event from the operating system. Based on the choice of font, the software converts the Unicode number into an image.

The software creates a binary representation of the image and sends it back to the CPU. The GPU translates the binary representation into the image displayed on your monitor. What about when keyboards have symbols in different locations? How might your operating system understand an Arabic keyboard instead of the Latin alphabet?

Why not share your thoughts and join in the discussion in the comments section below. Share this post. It was really informative for 12 Sep, It was really informative for me.

Visit the course. Clear structure 09 Sep, There is a good range of questions to challenge your understanding of the content discussed A good course 26 Oct, The course was very good 05 Nov, Intellectual skills 23 Aug, Understanding Computer Systems 26 May, The ideas are presented in a way that is easy to understand Excellent course 15 Jun, A good guide for teachers 24 May, A character map is basically a comparison chart or lookup table. It tells the processor the position of each key in the matrix and what each keystroke or combination of keystrokes represents.

For example, the character map lets the processor know that pressing the a key by itself corresponds to a small letter "a," but the Shift and a keys pressed together correspond to a capital "A. A computer can also use separate character maps, overriding the one found in the keyboard. This can be useful if a person is typing in a language that uses letters that don't have English equivalents on a keyboard with English letters.

People can also set their computers to interpret their keystrokes as though they were typing on a Dvorak keyboard even though their actual keys are arranged in a QWERTY layout. In addition, operating systems and applications have keyboard accessibility settings that let people change their keyboard's behavior to adapt to disabilities.

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